1,2,3-Thiadiazoles are disclosed in JP-A-2-149579/1990 as an agent for treating central nervous system diseases, in JP-A-54-9272/1979, JP-A-3-181463/1991, JA-A-4-234881/1992, Canadian Patent 947297, etc. as a herbicide or a plant growth regulator, and in WO 9501340 and JP-A-7-252242/1995 as a fungicide.